TS-530S Tuneup & RF in Shack

Discussion in '"Boat Anchor" & Classic Equipment' started by KB1RHB, Dec 10, 2019.

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  1. KB1RHB

    KB1RHB Ham Member QRZ Page

    Newbie here. Watched several videos on youtube, and a couple of websites
    about topic. Some questions -

    Note antenna is ~ 130 feet longwire, end fed in shack thru short (3 feet) section coax.
    I keep CAR control to ~ 10 W in TUNE mode when peaked. CAR control ~ 20%
    from CCW position.

    I have checked rig V, screen, seems to be close to spec in service manual. I
    also repaired 5 ohms Cathode R's (I burned them up in CW mode, lesson
    learned). Plate V also seems in spec, 10%.

    Tuneup (TUNE mode) -

    1) The peak and dip seems to work fine on 160, 80, above that
    peaks fine but no dip with PLATE control, in fact a pronounced
    peak just like the DRIVE control when adjusting the PLATE control.

    2) 160, 80 LOAD significant effect just like DRIVE, higher bands LOAD fairly small

    RF in Shack -

    I have a small wall wart powered PC speaker on my PC. When RF is in
    shack it causes a buzz in speaker. Also my oscilloscope probe will pick up
    RF if probe anywhere near short run of coax to wire.

    1) I assume this is due to antenna, 1 wavelength long, has highest E field at end
    of wire, feed point.

    2) If I feed as center fed dipole this problem goes away ?

    3) End fed like this do I have to be concerned about fire where wire comes close to
    house and/or passes under the window sill into the shack ? Due to arcing (I have not
    seen any yet) like on a humid day and house siding wet.

    This is a tad long winded, and thanks for help in advance.

    Regards, Dana.
  2. KA9JLM

    KA9JLM Ham Member QRZ Page

    My guess is that you need the other half of the antenna.

    A counterpoise.

    2) If I feed as center fed dipole this problem goes away ? = Yes

    Good Luck.
  3. WR2E

    WR2E Ham Member QRZ Page

    I have no RF to speak of in the shack.

    One brand of computer speaker BUZZES! REAL loud when I transmit.

    Another brand works perfectly.

    Don't assume that because your computer speakers buzz that you have an RF issue, although given your setup, you might.
    K9ASE likes this.
  4. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Some thoughts in no particular order:

    - Buy or build a dummy load capable of at least the full power of your rig. That helps in several ways including not doing all your tune up on the air but mainly it lets you untangle rig tuneup issues like strange dip and load behaviors from antenna problems. Right now it's hard to know whether you have rig issues or just antenna issues but tuning up the rig into a known 50 ohm dummy load can help separate those problems.

    - I'm surprised you can load the rig effectively on 160m with your 130 foot end fed which is a half wave antenna on 80m but only 1/4 wavelength long on 160m. I wouldn't recommend using a 130' end fed with the typical 49:1 or 64:1 matching transformer on 160m though you should be fine on the standard (non-WARC) bands from 80m and higher in frequency.

    - As posted above since you don't have much coax between the shack and the feed point of the antenna you may benefit from hanging about 8 to 12 feet of wire from the counterpoise lug on your antenna's matching transformer.

    - But that short coax also implies the feed point of your antenna is only 3' from your operating position. Your RFI problems may be coming from the close proximity of your transmitting antenna as much as any potential common mode on the coax. Transmitting antennas do of course transmit RF energy so it's a good idea to move them further from your home and sensitive electronics if possible.

    - As posted above, powered speakers are notorious for RFI pickup and that may not indicate a common mode problem as much as an antenna proximity problem along with the fact that many powered PC speakers act as unintentional crystal radios and are prone to reacting to even relatively low levels of RFI but all bets are off with your antenna so close to your shack.

    - If you can string up something like a simple dipole, even if it just covers one of the current problem bands it can help you separate some of the issues above. For instance if you can string up a simple 20m or 10m dipole fed with coax and get that antenna further from your shack you can at least see if that helps with your speaker noise and tune up issues. Alternatively you could try to re-string your end fed such that the overall antenna and the feed point is further from your operating position (e.g. coax up to the home's eaves maybe at the corner of your house and place the feed point transformer up there instead of right outside the shack) which should help in a couple of ways including adding more coax shield to act as counterpoise and moving the radiating antenna further from your operating position. If you do move your antenna further from your shack then a good RF common mode choke about 10' down your coax from the matching transformer may help as well.

    - One thing to check on the TS-530S dip and load behavior. Try setting the Load control to minimal loading (fully CCW) as you attempt to tune up on the problem bands where you don't see a pronounced dip in plate current via the Tune/Plate control. If you get a good dip there you may have just been running too much loading on the higher frequency bands but if you only get a good dip with minimal loading and at relatively low plate current but then the dip behavior goes away as you try to increase loading and you can't bring the plate current (and power) up in steps as you increase loading then you may have an issue with something in the output chain such as a bad RF coupling capacitor, a bad T/R relay or even a bad antenna connector or coax jumper as one sign of an RF path break in the output chain is ability to dip the rig at minimal loading but inability to raise the plate current towards nominal full output level with the Load control while still being able to achieve a dip via the Tune control. Again a dummy load will help to separate these issues from antenna issues.

    - And lastly I wouldn't operate your TS-530S until you can sort out the dip and load issues. If you don't see a pronounced dip in plate current and can't adjust the Load control for near rated current (no more than 225 mA) on some bands then I wouldn't run the rig on those bands as you risk blowing through final tubes and more cathode resistors and potentially other parts.
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    You're using a 130' end-fed, directly fed (3' of coax is about the same as direct feed), without using an external antenna tuner?


    That should only work on 160m where it's current-fed and I'm astonished it works on 80m where it's voltage-fed -- that's almost amazing!

    When you get no plate current dip and the LOAD control does almost nothing, assuming the rig's plate tank circuitry isn't damaged already, that generally indicates your antenna impedance is way out of range of anything the pi-network can match, which wouldn't be a surprise if you're not using an external antenna tuner.

    If you center-feed the same 130' of wire, you have an 80m dipole that should work and load up fine on 80m -- only. It might come close to loading up on 30m and 17m also, but not on 40m or 20m or 15m or 10m. To put a center-fed 80m doublet into service on several bands (80 through 10m, anyway), feed it with balanced line and not coax, and use a good manual antenna tuner in the shack having a current balun at its terminals (or use a more rare "balanced line" tuner). Another alternative which will allow coax feed and still work is to make it a multi-element parallel dipole, where each band has its own dipole elements (the 40m element can usually work on 15m also) all fed at the same point but with the wires separated by at least several inches; one more alternative that allows coax feed is to use traps for the higher bands, which makes the antenna heavier but does the job.
  6. K7TRF

    K7TRF Premium Subscriber QRZ Page

    I Ass-umed he was using a 130' End Fed Half Wave with the associated 49:1 or 64:1 feed point transformer and not directly feeding 130' of wire without any impedance matching at the feed point...

    But yeah, if it's just 130' of wire hung off the center conductor of the coax.... that pretty much won't work on bands besides 80m and maybe 30m especially without some kind of radials/counterpoise.
  7. N8YX

    N8YX Ham Member QRZ Page

    What I would do...since you have a TS-530S and always want to keep things matching (;) ) is to look around for an AT-230 antenna tuner. Once you've hooked it to the rig, install a good earth ground, tie the tuner and radio to it then hook your wire to the AT-230's random-wire connector.

    I'd also give consideration into making the wire a flat-top T or inverted L, with the vertical section as high as you can get it.

    Best bet is to use coax-fed resonant antennas with that setup but I've known quite a few people who have made the T/L approach work for them. And +1 to the other posters who mentioned getting a dummy load. The Kenwood tuner even has a rear-panel connector for one, so you can leave it permanently connected then switch to it when time to tune the rig up.
    W6BRY likes this.
  8. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Actually, if it's a directly fed 130' of wire, the only band where it would be current fed and likely to match well enough for the rig is 160m, not 80m.

    On 80m it would be voltage-fed and likely to not load up at all.
  9. K7TRF

    K7TRF Premium Subscriber QRZ Page

    Yeah, didn't think that through when I wrote it and yup it would be quarter wavelength on 160m not on 80m. I'm still curious as to whether this is actually a direct fed piece of wire or one of the popular EFHW antennas with appropriate matching transformer as I assumed.
  10. KB1RHB

    KB1RHB Ham Member QRZ Page

    I have the Kenwood 230 tuner, not yet using it. I do feed TS530 directly end fed into longwire.
    I also have a MFJ tuner with a dummy load in it, and balanced or unbalanced long wire antenna
    outputs, as well as coax ones. But I have not used it to tune.

    I do have a dummy load good for 300W. I will tune up on all bands into dummy load to see what I get.

    Point of confusion, I think of the LOAD and DRIVE controls as controlling a matching network,
    eg. a "tuner". So adding another tuner, a tuner on top of a tuner so's to speak, is confusing to
    say the least.

    So if I hook up AT-230 how does that change the tuneup procedure of the TS530 controls
    and the AT230 controls. Do I think of the external tuner as a 50 ohm R load, like a dummy,
    its transceiver connection side, and its controls the match to the antenna, its output to antenna
    side ?

    I am grateful to all that have commented, learned a lot already.

    I assume the matching transformer K7TRF mentioned is because driving end fed the
    point of drive is high V, near zero current, so Z is very very high ? The ratios mentioned
    mean that 50 ohms is translated to 49 or 64 X 50 = 2450 or 3200 ohms ? Thats of course
    at resonance ?

    Regards, Dana.
    Last edited: Dec 11, 2019

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